Perch is a 15-year-old agent of the White Pegasus Company, operating under Edward Chi alongside his identical twin brother, Noin. Despite their twin status, Perch and Noin possess contrasting physical traits, including distinct skin tones and hair colors. Their missions focus on stealing MoParts—artefacts tied to the ancient Motarian civilization—by targeting the staff of Monthly Moso Science through elaborate schemes.

Perch's Motarian transformation manifests as a polar bear, while Noin becomes a black bear. Together, they fuse into a single massive panda bear Motarian, drastically boosting their combat power for critical confrontations. This fusion deploys during pivotal battles, such as stalling the protagonists when Edward Chi is incapacitated.

As recurring antagonists, Perch and Noin persistently pursue the main characters through comedic yet determined efforts. In one operation, they disguise as mascots at a dog competition to steal MoParts but fail amid unexpected chaos. During a theater performance mission to intercept a MoPart, the artefact triggers unforeseen transformations and musical disruptions, foiling them again.

Their unwavering loyalty to Edward Chi culminates in joining the final battle against the protagonists to protect him after he sustains critical injuries.